1. Field of the Invention
This invention relates to the field of current carrying devices and components. In particular, the invention relates to a current carrying device including a substrate and a conductive layer.
2. Description of the Related Art
Current carrying structures are generally developed using a process in which a substrate is subjected to a series of manufacturing steps. Examples of such current carrying structures include printed circuit boards, printed wiring boards, backplanes, and other micro-electronic types of circuitry.
The manufacturing steps are typically performed on a substrate made of rigid, insulative material such as epoxy-impregnated glass fiber laminate. Conductive material such as copper is formed according to a pattern defining conductors, including ground and power planes.
Some previous current carrying devices are manufactured by layering a conductive material over a substrate. A mask layer is then deposited on the conductive layer. The mask layer is exposed and developed. The resulting pattern determines select regions where conductive material is to be removed from the substrate. The conductive layer is removed from the select regions by etching. The mask layer is subsequently removed, providing a patterned layer of conductive material on a surface of the substrate.
In other known processes, an electroless process is used to deposit conductive lines and pads on the substrate. A plating solution is applied to enable conductive material to adhere to the substrate on selected portions of the substrate to form patterns of conductive lines and pads.
To maximize available circuitry in a limited footprint, substrate devices sometimes employ multiple substrates, or use both surfaces of one substrate to include componentry and circuitry. The result in either case is that multiple substrate surfaces in one device need to be interconnected to establish electrical communication between components on different substrate surfaces.
Previous devices develop sleeves or vias that extend through the substrate. In multi-substrate devices, vias extend through at least one substrate to interconnect one surface of that substrate to a surface of another substrate. The sleeves or vias are provided with conductive layering to establish an electrical connection between the substrate sides being interconnected. In this way, an electrical link is established between electrical components and circuitry on two surfaces of the same substrate, or on surfaces of different substrates.
With previous devices, vias can be plated by seeding surfaces with conductive materials. During an electrolytic process, the surfaces of the vias are plated by bonds formed between the seeded particles and the plating material.
In other devices, via can be provided with a layer of conductive material using adhesives. In these devices, the bond between the vias and conductive material is mechanical in nature.
Certain materials, referred to below as voltage switchable dielectric material, have been used in previous devices to provide over-voltage protection. Electrical resistance properties of such materials regulate voltage surges from, for example, lightning, static discharge, or power surges.
Voltage switchable dielectric material are included in some devices, such as printed circuit boards. In these devices, voltage switchable dielectric material is inserted between conductive elements and the substrate to provide over-voltage protection.
In an embodiment of the invention, a substrate comprises a voltage switchable dielectric material. A current carrying formation is formed on a plurality of selected sections of a surface of the substrate.
In another embodiment, a substrate comprises a voltage switchable dielectric material. The substrate includes a first surface and a second surface opposite to the first surface. A via extends between the first surface and the second surface of the substrate. A current carrying formation is formed on a plurality of selected sections of the first and second surfaces, as well as on a surface of the substrate defining the via to extend an electrical connection from the first surface to the second surface.
In another embodiment, a multi-substrate device includes a first and second substrate. The first substrate comprises a voltage switchable dielectric material. A first current carrying formation is formed on a plurality of selected sections of a surface of the first substrate. The second substrate comprises the voltage switchable dielectric material. The second substrate is positioned adjacent to the first substrate. A second current carrying formation is formed on a plurality of sections of a surface of the second substrate.
Another embodiment includes a substrate comprising a voltage switchable dielectric material, and a current carrying formation formed on a plurality of selected sections of a surface of the substrate. The current carrying formation is formed on the surface of the substrate by a process that includes contacting the substrate with a current carrying formation precursor while applying a voltage to the substrate that is sufficient to cause the substrate to be conductive.
Another embodiment of the invention includes a substrate that comprises a voltage switchable dielectric material. The substrate includes a first surface opposing a second surface on the substrate. A via extends between the first surface and the second surface. A current carrying formation is formed on a plurality of selected sections of the first and second surfaces, as well as on the surface of the substrate defining the via. The current carrying formation is formed on the substrate by one or more processes, each process including contacting the substrate with a current carrying formation precursor while applying a voltage to the substrate that is sufficient to cause the substrate to be conductive.
In another embodiment of the invention, a multi-substrate device includes a first substrate comprising a voltage switchable dielectric material. A first current carrying formation is formed on a plurality of selected sections of a surface of the first substrate, where the first current carrying formation is formed by a process that includes applying a first voltage to the first substrate that is sufficient to cause the first substrate to be conductive. The device also includes a second substrate comprising a voltage switchable dielectric material. The second substrate is positioned adjacent to or stacked on the first substrate. A second current carrying formation is formed on a plurality of selected sections of a surface of the second substrate, where the second current carrying formation is formed by the process that includes applying a second voltage to the second substrate that is sufficient to cause the second substrate to be conductive.
In another embodiment, a device includes a substrate comprising a voltage switchable dielectric material. A formation comprising current carrying material is positioned adjacent a plurality of selected sections of a surface of the substrate between the substrate and the formation, the current carrying material adjacent the substrate being electrobonded to the substrate.
In another embodiment of the invention, a device includes a first substrate comprising a voltage switchable dielectric material. A first formation comprises current carrying material positioned adjacent a plurality of selected sections of a surface of the first substrate, where the current carrying material adjacent the first substrate is electrobonded to the first substrate. The device also includes a second substrate comprising voltage switchable dielectric material, where the second substrate is adjacent the first substrate. A second formation comprising current carrying material is positioned adjacent to a plurality of selected sections of a surface of the second substrate, the current carrying material adjacent the substrate being electrobonded to the substrate.
In a variation, the device includes a via interconnecting the surface of the first substrate with the surface of the second substrate. The via is defined by a surface. The surface includes a layer of current carrying material that is electrobonded to the surface defining the substrate.
Another embodiment of the invention provides a method for forming a current carrying device, the method comprising: taking a structure comprising a voltage switchable dielectric material; applying a voltage to make the voltage switchable dielectric material conductive while electrodepositing current carrying materials on selected regions of the structure.
Another embodiment of the invention provides a method of for forming a current carrying device, the method comprising: taking a structure comprising a voltage switchable dielectric material; depositing a formation of current carrying material onto selected sections of a surface of the substrate, the current carrying material adjacent the substrate being electrobonded to the substrate.
In a variation to the embodiment, the method comprises forming a patterned non-conductive layer on the surface of the structure before subjecting the structure to the electrolytic process, the pattern of the non-conductive layer defining the selected regions where the current carrying materials form.
In a variation to the embodiment, the method includes patterning the non-conductive layer to form gaps in which the structure is exposed to an electrolytic solution while in the conductive state.
Another embodiment of the invention provides a method for forming a current carrying device, the method comprising: taking a first substrate comprising a voltage switchable dielectric material; forming a via within the first substrate; patterning a first non-conductive layer on a surface of the first substrate; depositing a current carrying precursor over the first substrate while applying a voltage to the first substrate that is sufficient to cause the first substrate to be conductive, a pattern of the first non-conductive layer causing the current carrying precursor to form a first current carrying formation on the surface of the first substrate and on a surface of the via and aligning a second substrate over the first substrate so that a current carrying portion of the second substrate is electrically contactable with the surface of the first substrate by way of the surface defining the via.
In a variation, the method comprises depositing a voltage switchable dielectric material to form the second substrate; patterning a second non-conductive layer on a surface of the second substrate; and depositing a current carrying precursor over the second substrate while applying a voltage to the second substrate that is sufficient to cause the second substrate to be conductive, a pattern of the second non-conductive layer causing the current carrying precursor to form a second current carrying formation on the surface of the second substrate.
In a variation to the method, the current carrying formation on the surface of the first substrate includes: immersing a portion of the first substrate including the surface and a portion of the substrate containing the vias in a solution; and directing electrolytes in the solution to the first substrate while applying the voltage to the first substrate that is sufficient to cause the first substrate to be conductive.
In another variation to the invention, applying the voltage to the first substrate that is sufficient to cause the first substrate to be conductive includes applying a periodic voltage having a positive amplitude that is sufficient to cause the first substrate to be conductive.
In another variation, applying the voltage to the first substrate that is sufficient to cause the first substrate to be conductive includes applying a rectified reverse periodic voltage having the positive amplitude that is sufficient to cause the first substrate to be conductive.
Under another embodiment of the invention, a semiconductor device includes a substrate upon which circuitry forming the functionality of the semiconductor device is positioned, wherein the improvement comprises: the substrate comprising a voltage switchable dielectric material, and a current carrying formation formed on a plurality of selected sections of a surface of the substrate.